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Asthma vs. Severe Asthma: Symptom Severity, Treatment, and Management

Asthma is a heterogeneous disease. Severe asthma (5–10% of asthmatics) is defined by ERS/ATS as asthma requiring high-dose ICS-LABA plus a second controller (or systemic steroids) to prevent uncontrolled symptoms, or remaining uncontrolled despite this therapy.

Key Differences

FeatureMild-Moderate AsthmaSevere Asthma
Symptom controlWell-controlled on low/medium ICS ± LABAPersistent symptoms despite high-dose ICS-LABA + add-on
Exacerbations≤1/year requiring OCS≥2/year requiring OCS, or hospitalization/ICU
Lung functionNormal or near-normal between flaresPersistent airflow limitation (FEV1 <80% predicted)
PhenotypesAllergic, non-allergic, exercise-inducedType 2-high (eosinophilic, allergic), Type 2-low (neutrophilic, paucigranulocytic), obesity-related
ComorbiditiesRhinitis, GERDChronic rhinosinusitis w/ nasal polyps, obesity, GERD, dysfunctional breathing, anxiety/depression

Risk Factors for Severe Asthma

  • Early-onset allergic asthma, family history, atopy
  • Obesity (mechanical + inflammatory)
  • Smoking (active/passive) – induces steroid resistance
  • Poor adherence, incorrect inhaler technique
  • Environmental exposures (pollution, allergens, occupational)
  • Psychosocial stress, health literacy barriers

Treatment Escalation (GINA 2024)

  1. Confirm diagnosis, adherence, inhaler technique, comorbidities.
  2. Step 4: Medium-dose ICS-LABA.
  3. Step 5: High-dose ICS-LABA + add-on:
    • Biologics (Type 2-high): Anti-IgE (omalizumab), anti-IL5/5R (mepolizumab, reslizumab, benralizumab), anti-IL4Rα (dupilumab), anti-TSLP (tezepelumab).
    • LAMA (tiotropium): Add-on bronchodilation.
    • Low-dose OCS: Last resort; minimize due to toxicity.
    • Bronchial thermoplasty: Select cases (smooth muscle reduction).

Prognosis and Monitoring

  • With biologics, many achieve remission (no exacerbations, OCS-free, normal FEV1).
  • Regular review: symptom control (ACT/ACQ), FeNO, blood eosinophils, spirometry, inhaler technique.
  • Multidisciplinary severe asthma clinics improve outcomes.

When to Refer

  • Uncontrolled on Step 4–5 therapy.
  • ≥2 exacerbations/year requiring OCS.
  • Suspected non-adherence or alternative diagnosis.
  • Need for biologic eligibility assessment.

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